Estimating Exposure

You may be able to get suitable vibration data from the equipment handbook, or from the equipment supplier. See Table 1 for examples of vibration levels HSE has measured on equipment in use. There are also some databases on the internet which may have suitable vibration data, for example the OPERC online service.

If you plan to use the manufacturer’s vibration data you should check that it represents the way you use the equipment since some data may underestimate workplace vibration levels substantially. Ask the manufacturer for an indication of the likely vibration emission of the tool when your employees are using it. If you are able to get vibration data from the manufacturer which is reasonably representative of the way you use the equipment, it should be suitable for you to use in estimating your employees’ exposure. However, if the only information available to you is the vibration emission declared in the equipment’s handbook, it may be safer to double this figure before using it for estimating daily exposures.

You also need to check, by observing them, how long employees are actually exposed to the vibration (ie the total daily ‘trigger time’ with the equipment operating and in contact with the employee’s hand(s)). Employees are unlikely to be able to provide this information very accurately themselves. You could observe and measure the trigger time over, for example, half an hour and then use the result to estimate the trigger time for the full shift. Alternatively, where the work task is repetitive, eg drilling large numbers of holes in masonry, you could measure the trigger time when drilling several holes and multiply the average by the number of holes typically drilled in a shift.

Table 1: Some typical vibration levels for common tools

Tool type

Lowest

Typical

Highest

Road breakers

5 m/s2

12 m/s2

20 m/s2

Demolition hammers

8 m/s2

15 m/s2

25 m/s2

Hammer drills/combi hammers

6 m/s2

 9 m/s2

25 m/s2

Needle scalers

5 m/s2

-

18 m/s2

Scabblers (hammer type)

-

-

40 m/s2

Angle grinders

4 m/s2

-

 8 m/s2

Clay spades/jigger picks

-

16 m/s2

-

Chipping hammers (metal)

-

18 m/s2

-

Stone-working hammers

10 m/s2

-

30 m/s2

Chainsaws

-

6 m/s2

-

Brushcutters

2 m/s2

4 m/s2

-

Sanders (random orbital)

-

7-10 m/s2

-

 

If the employee is exposed to vibration from more than one tool or work process during a typical day, you will need to collect information on likely vibration level and ‘trigger time’ for each one.

Once you have collected relevant vibration data and exposure times you will need to use an exposure calculator to assess each employee’s daily exposure (see HSE’s vibration web pages at www.hse.gov.uk/vibration).

Alternatively, you can use the simple ‘exposure points’ system in Table 2 to estimate the daily exposure.

Workplace vibration measurements

If you want to obtain vibration measurements for your own tools you will need to arrange for a competent person to carry out measurements for you using specialised equipment. Measurement results can be highly variable, depending on many factors, including the operator’s technique, the condition of the work equipment, the material being processed and the measurement method. The competence and experience of the person who makes the measurements is important so that they can recognise and take account of these uncertainties in producing representative vibration data.

Table 2: Simple ‘exposure points’ system

Tool vibration (m/s2) 3 4 5 6 7 10 12 15
Points per hour (approximate) 20 30 50 70 100 200 300 450

 

Multiply the points assigned to the tool vibration by the number of hours of daily ‘trigger time’ for the tool(s) and then compare the total with the exposure action value (EAV) and exposure limit value (ELV) points.

100 points per day = exposure action value (EAV)
400 points per day = exposure limit value (ELV)

Content courtesy of www.hse.gov.uk.

Testimonial:

Carillion - Neil Dunlop, Health and Safety Manager

“Carillion has been using the Reactec HAVmeter system on Network Rail Framework projects in Scotland since June 2009. Health and Safety is Carillion’s number one priority. We are committed to continually improving health and safety of the workforce.”